Electrical characterizations of PZT ceramics in large frequency and temperature ranges

Electrical properties of PbZr_0.75Ti_0.25O₃ ceramics have been characterized. The measurements have been made in frequency ranging from 20 to 2.10⁹ Hz and between 20 and 730 °C for low and medium frequencies. Typically at room temperature, the dielectric constant ′ is higher than 500 at 1 MHz whereas the loss tangent is close to 0.01. From ′(T) measurements, the Curie temperature of our sample has been determined at 320 °C. In the paraelectric state, ′(T) follows the empirical Curie–Weiss law near the phase transition which is of second order type. The increase of ′ observed at high temperatures and low frequencies in the paraelectric state are explained: this abnormal behavior is due to the migation of oxygen ions towards the electrodes, creating an additional non-ferroelectric interface which generates a Maxwell–Wagner effect.